Advances in data storage technology have provided for ever-increasing storage capability in devices such as DVD-ROMs, optical drives, and disk drives. In hard disk drives, for example, the width of a written data track has decreased due in part to advances in reading, writing, and positioning technologies. More narrow data tracks result in higher density drives, which is good for the consumer but creates new challenges for drive manufacturers. As the density of the data increases, the tolerance for error in the position of a drive component such as a read/write head decreases. As the position of such a head relative to a data track becomes more important, so too does the placement of information, such as servo data, that is used to determine the position of a head relative to a data track.
In existing self-servowriting techniques, servo-bursts of a phase-burst scheme must be written in separate passes (one per burst). Because of this, minor coherence-errors suffered during writing of the bursts contribute to significant written-in runout of the resulting pattern. The resulting written-in runout may be un-acceptable.